Closure unit for containers



Sept 5, 1944. R. w. THOMAS 2,357,62@

CLOSURE UNIT FOR CONTAINERS Filed April 28, 1941' FIGS Milli/17111101111153:

. INVENTOR ROSSWELL W. THOMA-S BY v T F"? a Patented Sept. 5, 1944 CLOSURE UNIT FOR conmmnns Rosswell W. Thomas, Birmingham, Mich, assignor to Phillips Petroleum Company, a corporation of Delaware Application April 28, 1941, Serial No. 390,823

'5 Claims. (Cl. 220-89) This invention relates to a closure for a container, More particularly this invention relates to a combination pressure and temperature controlled safety relief unit for containers or tanks used in the storage and utilization of liquefied gases, or gases under high pressures.

In recent years the increased demand for liquefled petroleum gases, both -industrially and domestically, has presented the industry with the problem of designing saferand more economical systems for supplying such gases. Containers used for storing and dispensing liquefied gases,

such as propane and butane, being subjected to high pressures are designed accordingly with an ample safety factor for ordinary conditions. However, additional safety devices must be provided to prevent the bursting of a container, as internal pressure generated in such a container, by the heat of a fire, for example, may rupture the wall and scatter the inflammable contents thereby augmenting or spreading the fire.

To guard against such an occurrence the pres.- ent method is to incorporate a separate pressure relief valve and a fusible metal plug or insert in openings made in the wall of the container. Where a single combined valve tap plug including a safety pressure relief valve and a fuse plug, as

plug for support, will be explosively expelled when the latter melts.

Other objects and advantages of this invention, not at this time more particularly enumerated, will be apparent from the following detailed description in conjunction with the accompanying drawing forming a part thereof, in which:

Figure 1 is a cross-sectional view through one embodiment of applicants structure, illustrating the same in connection with a container, which is fragmentarily shown, and a pressure relief valve shown in elevation;

Figure 2 is a similar view of a second embodiment, 1

Figure -3 is a view similar to that of Figure 1 of a third embodiment of applicant's invention,

Figure 4 is a transverse section taken on the line 4-4 of Figure 2 with fusible metal 23 removed from holes 4|, and

Figure 5 is a transverse section taken on the line 55 of Figure 3. I

illustrated in applicants U. S. Patent No.

2,172,311, issued September 5, 1939, is used a single large aperture is made in the wall of the con- Referring now more particularly to Figure 1 of the drawing, there isfragmentarily illustrated a wall of a container III, which may be of any suitable size-or type but which for the purposes of explaining this invention is adapted to contain fluids under pressure, such as liquefied petroleum gases which may be utilized as fuel upon release of the pressure. This container is provided with a circular aperture H in which is inserted the circular body member or housing I: formed with an annular shoulder I3 which is of greater diameter than the remainder of the housing, and which is formed to support the housing in position onthe container. Weld l4 secures and holds housing I2 in position on container [0, although any other suitable means of securing the housing to the cRmtainer may be used.

Centrally of the housing If is provided a cir- 0 cular .bore I5 extending part way through the combining the elements of each into a single device easily made and assembled in a liquefied gas container.

A further object of applicants invention is to provide a unitary device capable of protecting a temperature, the pressure within will not blow the relief-valve bodily from the wall of the container.

Since a pressure sufiicient to rupture the wall may be generated by heat on the container, it is very dangerous to have a relief valve not securely metals.

housing having the upper portion thereof screw threaded as at l6, while the lower portion presents a continuous annular wall ll in which fits a flexible packing ring I 8, made of resilient material, such as rubber or any other equivalently compressible material and including soft A second bore I9- of reduced diameter axially aligned with bore I5 is also provided and continues through the under face of the housing.

Screwed into bore l5 and the threads at It, is a second circular body member or plug 20 externally threaded on its upper portion to engage the threads at It. I This member is .of reduced diameter at its lower end so as to fit into bore I9 of housing l2. An annular shoulder 2| seats on attached to the wall, which depending on the fuse f c This re P 5 8 Pl h interior of cpntainer III in communication with the exterior thereof and is normally closed by a fusible metal filling 23, preferably of a metal having a melting point at about 165 degrees Fahrenheit, extending into the passage. Thus it will be seen that when the temperature surrounding container l reaches this point the metal will melt and either flow into the container or be blown from passage 22 by the increased pressure, thereby opening passage 22 and venting the container.

A second .circular bore or passage 24 also extends through plug 20, having a narrow restricted orifice at 25 to improve the popping action of the relief valve, hereinafter described, as will be understood by those skilled in this art. The lower portion of this bore is of enlarged diameter and screw threaded as at 26 to engage threads on the body of pressure relief valve assembly 21. This valve assembly is similar to a tire core valve as commonly used in the automotive industry for vehicle tires and its general operation will be readily understood by reference to applicants above described patent. It should be noted that this valve assembly is spring loaded having a coiled spring 21-A and an adjusting nut and locknut at 2'|B projecting inside of container i0. thickness of the supporting plug 20 as well as providing protection for the valve.

Kerf 28 adapted to receive a screw driver blade for purposes of assembling is cut into the upper face of plug 20.

Thus it will be seen that in the event metal 23 melts and bore 22 is opened allowing the container to vent, relief valve 21 is still securely held in place by the threaded engagement at 25 with plug 20 which in turn is threaded at l6 to housing 12.

Figure 2 illustrates a modified type of improved closure member for containers. Numeral III indicates a fragmentary part of a wall of a container similar to that of Figure 1, provided with a circular aperture, in which is inserted a circular body member or housing 29. This member is formed with an annular shoulder 30 having a greater diameter than the remainder of the housing and which serves to support housing 29 in position on container l0. Weld l4 secures and holds this member 29 to container l5, although any other suitable means of securing the member to the container may be used.

Centrally of housing 29 is provided a circular bore 3| extending part way through and having its upper portion screw threaded as at 32, while its lower portion presents a continuous annular wall 33 in which fits a flexible packing ring i8, made of resilient material, such as rubber or any other equivalent compressible" material. A second bore 34 of reduced diameter axially aligned with bore 3| is also provided and continues through the under face of housing 29.

Screwed into bore 3| and the threads at 32, is a second circular body member or plug 35 externally threaded on its upper portion to engage the threads at 32. This member is of reduced diameter at its lower end, so as to fit into bore 34 of housing 29. An annular shoulder 36 seats on packing ring l8 and forms a sealing engagement therewith between housing 29 and plug 35.

Plug 35 is centrally provided with a circular bore 31 extending from the upper face part way through and terminating in an annular wall 38. A second circular bore 39 of reduced diameter, internally threaded at 40 to engage threads on the exterior of the relief valve assembly 21 ex This feature permits a reduction in the v tends through plug 35 terminating in a restricted orifice at 25. -In the annular wall 38, Figure 4, a plurality of circular passages 4| are drilled terminating in the lower face of plug 35. Thus it will be seen that the central bore 31 of plug 35 communicates with the interior of container I through alignment with the passages 4| in wall After the relief valve assembly 21 is mounted in bore 33, the annular space in the interior of plug 35 is closed by the fusemetal 23. As shown in Figure 2 the fusemetal extends down and fills the passages 4| as well as closing the interior of plug 35. Any suitable manner of casting the fusemetal to close this area may be used. Preferably the metal is melted and poured in place. It will be seen from this that the relief valve 21 may properly function independently of the fusemetal and cannot be blown from the bore 33 in the event that a suflicient high temperature to melt the fusemetal 23 occurs. Passages 4| are cleared by the melting of the metal 23, thus providing additional means of venting the container but as herein above described, the relief valve assembly will remain in place and continue to operate.

r serted a circular body member or housing 43.

This member is formed with an annular shoulder 44 having a greater diameter than the remainder of the housing and which serves to support the housing in position on container l0. Weld l4 secures this housin to the container.

A central bore 45 extends part way through housing 43 threaded in its upper portion as at 45 and with its lower portion terminating in an annular wall 41 in which fits a flexible packing ring I 8.

Bore 43 of reduced diameter axially aligns with bore 45 and continues throughthe under face of housing 43.

Screwed into the threads at 45 of bore 45 is a sleeve or circular plug 49 externally threaded on its upper portion to engage the threads at 46 and having its lower portion adapted to seat on packing ring I8 and make a sealing engagement between housing 43 and sleeve 49. A central bore 5|! extends through the interior of sleeve 43 from its upper face through the lower face, thus communicatin'g with the bore 43 in housing 43. Recessed portions 5| and 52 are cut into the interior wall of sleeve 49 from bore 50 for Purposes hereinafter described.

A flat washer 53, see Figure 5, centrally bored and having projecting lugs 54 and 55 fits loosely into recessed portion 52 and serves as a lower base for the fusemetal 23 filling the annular space 51 in bore 50 between sleeve 43 and valve housing 56. By reference to Figure 5 it will be seen that washer 53 does not completely close bore 5|! when valve housing 56 is inserted, but leaves semi-annular spaces 51 open. Thus. when the temperature is sufilcientiy high to melt fusemetal 23 it will either flow through space 51 into container l0 and thereby clear the passage, or it will be blown out of its present position by the increased pressure generated within the container. In

a pressure relief valve held against removal from valve assembly 21 is mounted. Threads on the valve assembly 21 engage threads as at I! in the lower portion of the bore thus holding the valve assembly securely mounted within the housing 56. The upper portion of this bore in housing 58 terminates in a restricted orifice 2! which was found to improve the poppingaction of the valve.

Sleeve 49 terminates at its upper end in a tool socket slotted as at I to receive a tool head to b used in tightening the members or to facilitate their removal.

Assembly of this fuse plug, particularly the embodiments in Figures 2 and 3 is accomplished as follows: plug 35, Figure 2, is screwed into housing 2! seating on packing ring or gasket ll. Bore 31 of plug 35 i then filled with fusemetal 23 which upon hardening becomes an integralpart of the plug. Valve assembly 21 may then be screwed into th threads at 4..

Sleeve 49 of Figure 3, is screwed into housing 43, seating on ring ll then washer I3 is placed in recessed portion 52, and valve housing It is inserted. Annular space 51 is filled with fusemetal 23 which becomes an integral part of the sleeve member and which fills recessed portion 5| forming a shoulder. Shoulder II of housing 56 engages the lower side of washer I3 and Drevents the housing with valve assembly 21 screwed A therein from being blown from the container.

While I have described specific embodiments of my invention, it-is to be understood that the form of this invention, herewith shown, are preferred examples thereof and that various modifications may be made without materially departing from the spirit of the invention as defined by the appended claims.

Having thus described my invention. I claim:

1. A closure for containers comprising a plug removably secured to the containerand having two passages extending therethrough'connectlng the interior of the container with the atmosphere, one of said passages being concentric of the other passage and closed by a filling of fusible metal integral with the plug member, the other of said passages being normally closed by the container independently of the fusible metal. 2. A closure for containers comprising a plug removably secured to the container and having two passages extending therethrough connecting the interior of the container with the atmosphere, the first of said passages comprising in part an annular groove formed in the plug surrounding the other passage, said first passage being closed by a septum of fusible metal the other of said passages being normally closed by a pressure relief valve held against removal from the container independently of the fusible metal.

3. A closure for containers comprising a plug removably secured to the container and having two passages extending therethrough connectingthe interior of the container with the atmosphere, the first of said passages comprising in part a series of small orifices in the plug disposed substantially in a circle surrounding the .other passage, said first passage being closed by a septum of fusible metal the other of said passages being normally closed by a pressure relief valve held against removal from the container independently of the fusible metal.

4. A closure for containers comprising a plug removably secured to the container and havingtwo passages extending therethrough connecting the interior of the container with the atmosphere, the first of said passages comprising in part a series of small orifices in the plug dis- P sed substantially in a circle, an annular groove formed in the plug surrounding th other passage, and connected to said orifices, said first passage being closed by a septum of fusible metal the other of said passages being normally closed bye. pressure relief valve held against removal from the container independently of the fusible metal.

5. A closure for a container opening comprising plugging means having in combination a central cylindrical portion, a fluid pressure relief valve secured to and closing the interior of the central cylindrical portion, an annular outer portion, an annular septum sealing the inner portion to the outer portion comprising a sleeve of fusible metal cast integrally to the inner and outer portions, means on the outer portion for .removably securing the plugging means to the nosswszu. w. THOMAS. 

